[IMPALA-6449] Use CLOCK_MONOTONIC in ConditonVariable

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: Impala 2.7.0, Impala 2.8.0, Impala 2.9.0, Impala 2.10.0, Impala 2.11.0, Impala 2.12.0
• Fix Version/s: Impala 3.0, Impala 2.12.0
• Component/s: Backend
• Epic Color: ghx-label-9
• Assignee: Michael Ho
• Reporter: Michael Ho
• Created: 29/Jan/18 22:39
• Updated: 14/Mar/18 05:55
• Resolved: 14/Mar/18 05:55

Description

There are various places in the code which call ConditionVariable::WaitUntil() or ConditionVariable::WaitFor() with a time computed from boost::get_system_time().

  template <typename duration_type>
  bool WaitFor(boost::unique_lock<boost::mutex>& lock,
      const duration_type& wait_duration) {
    return WaitUntil(lock, to_timespec(boost::get_system_time() + wait_duration));
  }

blocking-queue.h:

  template <typename V>
  bool BlockingPutWithTimeout(V&& val, int64_t timeout_micros) {
    MonotonicStopWatch timer;
    boost::unique_lock<boost::mutex> write_lock(put_lock_);
    boost::system_time wtime = boost::get_system_time() +
        boost::posix_time::microseconds(timeout_micros);

thrift-server.cc:

  system_time deadline = get_system_time() +
      posix_time::milliseconds(ThriftServer::ThriftServerEventProcessor::TIMEOUT_MS);

  // Loop protects against spurious wakeup. Locks provide necessary fences to ensure
  // visibility.
  while (!signal_fired_) {
    // Yields lock and allows supervision thread to continue and signal
    if (!signal_cond_.WaitUntil(lock, deadline)) {

The above are susceptible to clock adjustment from various sources such as NTP. We should switch to using clock_gettime(CLOCK_MONOTONIC, ...) for such elapsed time measurement.